[tex4ht] bug with pagestyle headings

[Ulrike Fischer]

\documentclass{article}
\pagestyle{headings}

\begin{document}

\section{abc}

\end{document}

fails with 

! Missing \endcsname inserted.
<to be read again> 
                   \\endcsname 
l.58 \section{abc}

It compiles again if one remove the \MakeUppercase from \sectionmark:

\makeatletter
    \def\sectionmark#1{%
      \markright {{%
        \ifnum \c at secnumdepth >\m at ne
          \thesection\quad
        \fi
        #1}}}
\makeatother  

Ulrike